Book Description

Over one quarter of the energy usage in the United States currently occurs in the transportation sector. Improvements in energy conversion efficiency and sustainability in transportation applications, therefore, can substantially contribute to improved energy security in our future. The design of advanced high-efficiency energy conversion devices for transportation applications can be facilitated with complex computer models of combustion processes. The development of these models requires a large experimental database to ensure accuracy of the computational predictions. This thesis discusses how experimental studies are utilized to create a database of rate constants for elementary reactions; these rate constants are integral components of any computational model of combustion chemistry. During a combustion process, the reaction of the hydroxyl (OH) radical, a highly reactive chemical intermediate, with a combustible fuel molecule is a major fuel consumption pathway under many combustion conditions. Thus, the rate constants for these types of reactions must be accurately known to develop a computational model that correctly describes the combustion chemistry. This thesis presents an experimental method for measuring rate constants in the reaction family of OH + Fuel -> Products using a shock tube reactor, laser diagnostics, and tert-butylhydroperoxide (TBHP) as an OH radical precursor. Important rate constant parameters describing subsequent reactions of TBHP decomposition are also studied. Current transportation fuels of interest in the combustion community include molecules in the alkane and butanol classes. Alkane molecules are a major component of many petroleum-derived fuels such as gasoline and jet fuel. Isomers of the butanol molecule are gaining popularity as a potential renewable alternative to gasoline because of their high energy density and the many known methods of production from biomass and agricultural byproducts. The rate constant measurement method is applied to the reaction of OH with three alkane molecules (n-pentane, n-heptane, and n-nonane) and four isomers of butanol (n-butanol, iso-butanol, sec-butanol, tert-butanol), and the results are reported in this thesis. Comparison of the rate constant results to estimation methods in the literature are presented, and, for several of the isomers of butanol studied, the measured data are also used to validate and/or suggest refinements to existing detailed kinetic mechanisms.